The prevention and treatment of periodontal disease relies at least in part dental hygiene behaviors that are performed daily to remove plaque. The purpose of this project is to test strategies to promote and, in particular, maintain adherence co a dental hygiene regimen. Three experiments are proposed. Participants will be young adults referred from a dental office because they are "at risk" of having periodontal disease. Risk is defined using an index based on inflammation and bleeding (i.e., some gingivitis). The interventions to be tested all involve variables that are expected to influence two types of beliefs, drawn from Social Learning Theory, that have been shown to be related to regimen adherence in our previous work: self-efficacy expectations and outcome expectations. In Experiment 1, half the participants will receive a 3-session treatment that includes health education, skills training in plaque removal, and performance feedback. The other half will receive a less intense intervention that retains the crucial theoretical components but involves less time and behavioral expertise. Experimental participants will the" undergo frequent, repeated assessments to discover the processes underlying regimen relapse. In subsequent experiments, the best treatment from Study 1 (or, if they are equivalent, the less intensive treatment) will be used. In addition, a component will be added to foster maintenance of regimen behaviors. In Experiment 2, the effects of public commitment to the dental hygiene regimen will be examined. In Experiment 3, fear imagery will be contrasted with positive imagery as aids to adherence maintenance. Because of our emphasis on maintenance of behavior change, participants in all experiments will be followed for 1 year beyond treatment initiation. Primary outcome measures will include self- monitoring and unobtrusive measures of adherence behaviors, plaque levels and gingival bleeding. In addition, process measures (e.g., self-efficacy expectations; outcome expectations; the reactions of significant others) will be gathered co assess why treatments are effective or ineffective.